Our long-term interest is to understand how ion channels are localized to particular sub-cellular sites and regulated by specific protein interactors. In this grant proposal, we focus on the voltage-gated K+ channel, Shal (Kv4), which has been implicated in setting the rhythmic firing of central pattern generators, learning and memory, and shaping the cardiac action potential. Therefore, understanding the mechanisms of Shal K+ channel localization and regulation has important implications for vital processes in the heart and central nervous system. We focus our initial studies on two newly identified interactors, K30 and K29, of Drosophila Shal channels. Both interactors are expressed primarily in the nervous system, co-localize with Shal channels, and exhibit strong and specific binding to the C-terminus of Shal channels. Interestingly, K29 binds to a highly conserved motif required for dendritic targeting of mammalian Shal channels, implicating K29 as a key regulator of Shal channel localization. We will characterize Shal-K30 and Shal-K29 interactions and examine the function of K30 and K29 in the subcellular localization and regulation of Shal channels in vivo. Using Drosophila as a model system will allow us to combine genetic, electrophysiological, cell and molecular biological approaches to study how all identified interactors function in the regulation and subcellular localization of Shal channels. Since strategies and proteins identified are likely to be conserved in mammals, our findings are expected to be significant not only for understanding Drosophila ion channels, but also for mammalian systems. Relevance to public health: Ion channels are the basic components that shape electrical and chemical communication in the nervous system, and the function of ion channels is highly dependent on their subcellular localization and regulation. When ion channels are mis-localized or mis-regulated, consequences are often severe, resulting in conditions such as epilepsy, episodic ataxia, periodic paralysis, myotonia, and Long QT syndrome. Therefore, understanding how ion channels are regulated and localized to subcellular compartments is likely to give important insights into the prevention and treatment of these conditions.